This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Swedish Application No. 0101838-1 filed on May 23, 2001, the entire content of which is incorporated herein by reference.
This invention generally relates to continuous casting machine. More particularly, the invention pertains to a method for detecting a misaligned roller portion of a roller in a continuous casting machine.
A continuous casting machine produces steel material from molten steel. This steel material can, for example, be used as a starting material in rolling processes for producing sheet metal used in, for example, vehicles.
In the continuous casting machine, molten steel flows from a ladle and down in a tundish from which it is transported further down into a mold. In the mold, which is water-cooled, the slab of continuous cast material begins to form a solid shell. Then, the slab is continuously transported along a curved track by a large number of rollers arranged in segments, which continue to shape and cool the slab to the final thickness of the steel material. At the end of the track, the material is cut into suitable pieces.
The rollers of the continuous casting machine are mounted with their axes substantially perpendicular to the longitudinal extension of the curved track. To lead and support the slab of continuous cast material, the rollers are arranged in pairs each comprising an upper roller and a lower roller.
Further, the rollers are rotatably mounted in supporting members at each end of the rollers. Due to the length of the rollers and thus the load on the rollers, the rollers are generally split into at least two roller portions. The roller portions are either independently mounted in supporting members or non-rotatably provided on a common shaft, with the shaft being mounted in supporting members. The supporting members can be, for example, rolling bearings or sliding bearings. Further, the supporting member can also comprise a suitable bearing housing.
As described in the applicant""s Swedish Patent Application No. 0100612-1, the slab must be fully and evenly supported by the rollers to obtain a cast material with high quality. If the support is not satisfactory, cracks can arise in the material due to bending forces. These cracks can be either internal cracks or surface cracks, both types of which lead to decreased quality, as a material having cracks will be almost impossible to roll. Surface cracks can be treated by costly treatment after the casting process. One way of treating the surface cracks is to weld them while another way is to grind off the surface layer of the material. However, both alternatives are expensive and sometimes cannot give a perfect result. As a result, the steel may have to be classified in a lower quality class. Material with internal cracks cannot be treated and must be classified in a lower quality class or discarded.
Generally speaking, non-uniform support of the slab may be caused by different types of roller failures. The above-mentioned application describes a method for detecting roller failures which can be either bearing failures or mounting failures. Both types of failures lead to misalignments of single rollers and/or entire segments of rollers, i.e., the rollers and/or segments are not aligned with the longitudinal extent of the track of the continuous casting machine.
However, the application mentioned above does not deal with the problem of misaligned roller portions of a roller. As described above, the rollers are generally split into at least two roller portions that are either independently mounted in supporting members or non-rotatably provided on a common shaft, with the shaft being mounted in supporting members.
If the roller portions are provided on a common shaft, the alignment between the roller portions will naturally be correct. If the roller portions are instead independently mounted in supporting members, there is a need to adjust them to an imagined horizontal line forming a xe2x80x9crollerxe2x80x9d. The alignment of the roller portions of each roller is measured with conventional measuring equipment such as, for example, a ruler. Adjustments can be made, for instance, by using shims at the bearing housings.
Afterwards, several rollers are mounted together forming a segment, which segment is placed in the machine aligned with the longitudinal extension line of the track of rollers. During the mounting of these segments in the continuous casting machine, it is very likely that the alignment between the roller portions of the rollers is more or less destroyed or altered because of the size, weight and ungainliness of the segments.
When starting up the casting process, it is therefore important to check that all of the roller portions of a roller are correctly aligned with each other, i.e., so that the roller portions of a roller appear at or along an imagined horizontal line, with such horizontal line in turn being aligned perpendicular to the longitudinal extension (longitudinal extent) of the track of rollers. Unfortunately, it is usually very difficult to distinguish or identify a misaligned roller portion because the distance between a correctly aligned roller portion and a misaligned roller portion is typically very small.
Therefore, a need exists for a method for detecting a misaligned roller portion of a roller in a continuous casting machine.
According to one aspect, a method is provided for detecting a misaligned roller portion of a roller in a continuous casting machine, wherein the machine includes a plurality of rollers arranged in a row after each other, with the rollers being divided into at least two roller portions each rotatably mounted in supporting members and arranged for transporting produced material. The method includes measuring the radial load exerted by the material on each supporting member of the roller portions of a roller, comparing the radial load values of the supporting members arranged in the outer ends of the roller with each other, comparing the radial load values of the supporting members arranged in the inner ends of the roller with each other, and establishing the presence of a misaligned roller portion where the divergence between the load values of the supporting members of the outer ends of the roller and/or the supporting member of the inner ends of the roller are exceeding a predetermined value.
In accordance with another aspect, a method for detecting a misaligned roller portion of a roller in a continuous casting machine includes transporting material produced in the continuous casting machine along a plurality of rollers arranged in a row one after another, with at least one of the rollers being divided into at least two roller portions positioned axially adjacent one another and each rotatably mounted in two supporting members so that a supporting member is arranged at a first end of each roller portion and at a second end of each roller portion. The method also includes measuring a radial load value exerted by the material on the supporting members arranged at the first ends of the roller portions or the supporting members arranged at the second ends of the roller portions, comparing the measured radial load values of the supporting members with each other, and determining at least one of the roller portions is misaligned when the comparison of the measured radial load values of the supporting members reveals that a divergence between the measured radial load values of the supporting members exceeds a predetermined value.
According to another aspect, a method for detecting a misaligned roller portion of a roller in a continuous casting machine includes transporting material produced in the continuous casting machine along a plurality of rollers arranged in a row one after another, with at least some of the rollers being divided into at least two roller portions positioned axially adjacent one another and each rotatably mounted in supporting members so that a supporting member is arranged at each outer end of the at least one roller and at each inner end of the at least one roller, measuring a radial load value exerted by the material on the supporting members arranged at the outer ends of at least one roller, measuring a radial load value exerted by the material on the supporting members arranged at the inner ends of at least one roller, comparing the radial load values of the supporting members arranged at the outer ends of the at least one roller with each other, comparing the radial load values of the supporting members arranged at the inner ends of the at least roller with each other, and establishing that at least one of the roller portions is misaligned when a divergence between the radial load values of the supporting members at the outer ends of the at least roller and/or where a divergence between the radial load values of the supporting members of the inner ends of the at least one roller exceed a predetermined value.